How heavy are they in-game (How hard for zombies/humans to move around).

Do they work with all prop types (excluding detail)?

And they do look nice, particularly the lamp.

They work as prop_physics_multiplayer and prop_physics_override. I set their weight to 20 (lamp is less) which is pretty low, but you can change that in hammer with the multiplier thing. I think it's called mass scale override, something like that. I haven't tried using them as static props, but they were compiled without $staticprop in the .qc so if they don't work as static but you want them stuck try making them dynamic props with motion disabled.